Phytotherapy

Phytotherapy is the use of plants and plant-derived preparations to treat or prevent illness. It is the therapeutic application of medicinal plants, drawing on traditional use and, increasingly, on chemical standardisation and clinical evaluation of the preparations involved.

Definition

Phytotherapy is the treatment or prevention of illness using plants or preparations made from them, where the therapeutic agent is typically a multi-component plant extract rather than a single isolated compound.

Scope

The topic covers what distinguishes phytotherapy from the use of isolated single-compound drugs, the concept of the whole plant extract as the active entity, the importance of standardisation and quality for reproducible effects, and the place of clinical evidence in evaluating herbal therapies. It is framed as a reference topic describing the practice and its scientific basis, not as treatment instructions or dosing guidance.

Core questions

• How does phytotherapy differ from treatment with isolated single-compound drugs?
• Why is standardisation of herbal preparations important for reproducible effects?
• What kinds of evidence are used to evaluate the efficacy and safety of phytotherapeutic preparations?

Key concepts

• Whole extract as active entity
• Phytochemical complexity and possible synergy
• Standardisation and marker compounds
• Quality, safety, and herb-drug interactions
• Clinical evaluation of herbal preparations

Mechanisms

In phytotherapy the therapeutic effect is usually attributed to a complex mixture of plant constituents rather than a single molecule, and the composition of that mixture depends on the source material, extraction, and preparation. Because effects can vary with this composition, standardisation, defining the preparation against marker or active constituents, is central to obtaining reproducible activity and to comparing products. Evaluating phytotherapy therefore combines characterisation of the preparation's chemistry with assessment of its pharmacological and clinical effects.

Clinical relevance

Phytotherapeutic preparations are widely used, and assessing their quality, efficacy, safety, and potential interactions with conventional drugs is part of pharmacy and clinical practice. This topic describes the principles by which such preparations are studied and standardised and is not a basis for individual diagnostic or treatment decisions, and it provides no dosing guidance.

Epidemiology

Use of herbal and plant-based remedies is common worldwide, including alongside conventional medicines, but the prevalence and patterns of use differ markedly by country, product, and survey method.

Evidence & guidelines

The WHO Traditional Medicine Strategy 2014-2023 addresses the regulation and rational use of herbal medicines. Reviews of plant-derived therapeutics document where standardised preparations and clinical evidence support particular uses, while emphasising that evidence quality varies across products.

History

Treating illness with plants predates written medicine and is central to historical materia medica. Modern phytotherapy developed as pharmacognosy and analytical chemistry made it possible to characterise and standardise extracts, and as clinical research methods were applied to evaluate herbal preparations more rigorously.

Debates

Whole extract versus isolated compound

A recurring question is whether the therapeutic value of a medicinal plant resides in a single active constituent or in the combined action of multiple compounds in the whole extract; the answer affects how preparations should be standardised and evaluated.

Key figures

• Norman Farnsworth
• Gordon Cragg
• David Newman

Seminal works

• fabricant-farnsworth-2001

Frequently asked questions

How is phytotherapy different from herbal medicine in general?

Phytotherapy specifically denotes the therapeutic use of plant preparations to treat or prevent illness, often with attention to standardisation and clinical evaluation. 'Herbal medicine' is a broader umbrella that also includes traditional practices and the preparations themselves.

Why does standardisation matter in phytotherapy?

Because a plant extract is a complex mixture whose composition can vary with the source material and preparation, standardising it against defined constituents helps ensure that products are consistent and that effects observed in studies can be reproduced.